1. Field of the Invention
This invention relates to an X-ray photographic apparatus which is capable of preventing the overshoot of tube current at the start of the X-ray radiation.
2. Prior Art
In the X-ray photographic apparatus of the prior art, the X-ray tube voltage is adjusted to a desired value before photographing to unify the intensity of X-ray to be radiated. However, this adjustment is troublesome, and a commercially available power supply for the X-ray photographic apparatus may frequently fluctuate during the period between the adjustment and photographing. As a result, the fluctuation of the filament current and the tube voltage cannot be prevented, and makes it difficult to radiate X-ray in a uniform intensity.
In another prior art, an X-ray tube voltage supply circuit and an X-ray tube filament driving circuit including a constant voltage transformer, etc. are used to eliminate the necessity for the preset adjustment. However, this approach cannot effectively confront the fluctuation of the X-ray tube current due to the deterioration of the X-ray tube occurring after the use for an extended period and to the variation of environmental temperature.